Unable to render pages when on bad internet connection

[YorickPieters]

When browsing an eBook and my mobile data connection is not good anymore, the app does not render the html. We get an ERR_CONNECTION_TIMED_OUT error message.

[YorickPieters]

Occurs on: Play Store version (seen on both beta 1 and beta 2)
App version: 1.0.1
Github tag: v1.0.0-beta.2

Steps to reproduce:

• Place device in flight mode
• Open R2 Reader
• Click on a publication
• You get an error "Webpage not available" with error code ERR_PROXY_CONNECTION_FAILED

or

• Go to a place with bad mobile data connection
• Open R2 Reader
• Click on a publication
• You get an error "Webpage not available" with error code ERR_CONNECTION_TIMED_OUT

[HadrienGardeur]

I can't reproduce this issue on my Pixel 2XL running Android 9.

[YorickPieters]

I'll try and gather more info on when it occurs. It does not always seem to trigger, just now I was able to work in flightmode again. It seems to occur mostly on one of my 2 mobile data connections, I even got a DNS lookup failed error at some point.

[llemeurfr]

Yes, as this is not visible on my android tablet when I put it in flight mode. And the local server should not be impacted by bad mobile connectivity.

[YorickPieters]

Additional information. The cause of this issue seems to be that one of my Mobile Data (base gprs) providers had a proxy active. If I disable the proxy server for that provider the app works fine.
It is weird that Android would allow a localhost call to be passed on to that proxy.
One of my colleagues found a similar report on this project: syncthing/syncthing-android#440

[llemeurfr]

Reading the syncthing thread, seems there is no solution that doesn't involve a modification of the device config by the user. If true, that would be a mess.

[HadrienGardeur]

We need to investigate ASAP if this is still an issue.

[mickael-menu]

I'm closing because I can't reproduce and I don't think we got any more similar report since then. R2 has been used in production for a while now.

This other issue that we'll tackle soonish should render this moot anyway: https://github.com/readium/r2-testapp-kotlin/issues/297